AUTO RANGING CAT III 600V

DIGITAL MULTIMETERUSER’S MANUAL

DMM45Please read this manual carefully and thoroughly before using this product.

TABLE OF CONTENTSIntroduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3Key Features . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3What's in the Blister Pack . . . . . . . . . . . . . . . . . . . . . . . . . 4Product Overview. . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4 – 5Safety Instructions. . . . . . . . . . . . . . . . . . . . . . . . . . . . 5 – 8Setup Instructions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8Install Batteries . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8

Operating Instructions . . . . . . . . . . . . . . . . . . . . . . . . 9 – 13General Instructions . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9

Using Auto Ranging . . . . . . . . . . . . . . . . . . . . . . . 9Turning On the Backlight . . . . . . . . . . . . . . . . . . . 9Auto Power Off . . . . . . . . . . . . . . . . . . . . . . . . . . . 9

Measuring AC or DC Voltage . . . . . . . . . . . . . . . . . . . . . 10Measuring AC or DC Current . . . . . . . . . . . . . . . . . 10 – 11Measuring Resistance. . . . . . . . . . . . . . . . . . . . . . . . . . 11Measuring Temperature . . . . . . . . . . . . . . . . . . . . . . . . 12Checking for Continuity. . . . . . . . . . . . . . . . . . . . . . . . . 12Checking the Integrity of a Diode . . . . . . . . . . . . . . . . . 13

Specifications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14 – 15Operating & Maintenance Tips. . . . . . . . . . . . . . . . . 15 – 16

Replacing the Fuse. . . . . . . . . . . . . . . . . . . 15 – 16Warranty Information . . . . . . . . . . . . . . . . . . . . . . . . 17 – 18Return for Repair Policy . . . . . . . . . . . . . . . . . . . . . . . . . . 18

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INTRODUCTIONThank you for purchasing General Tools & Instruments’(General’s) DMM45 Auto Ranging CAT III 600V DigitalMultimeter. Please read this user’s manual carefully andthoroughly before using the instrument.

The DMM45 is designed for use in an industrial setting byHVAC/R contractors, building maintenance technicians, MRO(maintenance, repair and operations) personnel at processand power plants, electricians, and electrical/electronictechnicians.

The meter is affordable, reliable, easy to use, ruggedly builtand designed to meet the CAT III 600V safety standard.

KEY FEATURES• 8 functions, 25 ranges

• Measures 1) AC voltage over five ranges, 2) DC voltageover five ranges, 3) DC current over four ranges, 4) ACcurrent over four ranges, 5) resistance over six ranges,and 6) temperature over one range using included “K”type stem thermocouple probe

• Uses beeper to 7) verify integrity of diodes and 8) checkcircuits for continuity

• Large backlit 3-1/2 digit (2,000 count) LCD

• LIGHT (backlight) button• 15 minute Auto Power Off (APO)

• Designed to meet CAT III 600V safety standard

• 1 year limited warranty

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WHAT’S IN THE BLISTER PACKThe meter is supplied in a blister pack with a cavity in therear. Inside the cavity are a pair of double-insulated 20AWGtest leads, a “K” type stem thermocouple probe, and two“AAA” batteries. This user’s manual is supplied inside thefold-over blister card.

PRODUCT OVERVIEWFig. 1 shows the labels and positions of the controls,indicators and physical structures of the DMM45. Fig. 2shows all possible indications on the meter’s LCD. Familiarizeyourself with the functions and meanings of these controls,indicators and connectors before moving on to the SetupInstructions and OperatingInstructions.

Fig. 1. The controls, indicatorsand physical structures of the DMM45.1. LCD

2. LIGHT button. Pressed andheld for >3 seconds, turnson display backlight for 15seconds. Pressed and heldwith backlight on, turnsbacklight off.

3. SHIFT button. Used to toggle between 1) AC and DC currentmeasurement modes, 2) continuity and diode integritycheck modes, and 3) °F or °C display of temperature

4. Rotary function switch 5. Jacks for test leads

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2

1

3

4

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Fig. 2. All possible display indications

SAFETY INSTRUCTIONS•WARNINGTo avoid possible electric shock or personal injury, and toavoid damaging the meter or the equipment under test:• Do not use the meter in any way not detailed in this manualor the meter's safety features may be compromised.

• Before using the meter, inspect the case. Do not use the meter if it is damaged. Look for cracks ormissing plastic. Pay particular attention to the area near thetest lead jacks.

• •WARNING Inspect the test leads for damaged insulationor exposed metal. Check the test leads for continuity.Replace damaged leads before using the meter.

• Verify the meter’s operation by measuring a known voltage.Do not use the meter if it operates abnormally. Protectionmay be impaired. When in doubt, have the meter checkedand serviced by a qualified technician.

• •WARNING Do not apply more than the rated voltage, asmarked on the front of the meter, between the terminals orbetween either terminal and ground.

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• •WARNING Do not measure current above 600V inCategory III installations.

• •WARNING Do not measure voltage with the rotaryfunction switch in any resistance (ohms) or current position.Doo not measure current with the rotary function switch inany resistance position.

• Use caution when working with voltages above 42VACRMS,or 60VDC. These voltages pose a shock hazard.

• Use the proper terminals, function, and range for allmeasurements.

• •WARNING Do not operate the meter around explosivegas, vapor, or dust.

• •WARNINGWhen using the test leads, keep your fingersbehind the finger guards. Do not touch the metal probes ofthe test leads when making a measurement.

• When making connections, connect the black (–) test leadbefore connecting the red (+) test lead; whendisconnecting, disconnect the red (+) test lead beforedisconnecting the black (–) test lead.

• Disconnect circuit power and discharge all high-voltagecapacitors before measuring/testing for resistance,continuity or diodes.

• Before making DC voltage measurements, verify that ACvoltages are not present by making measurements in ACvoltage mode. Then select a DC voltage range equal to orgreater than the AC range.

• Before measuring current, turn off power to the circuitbefore connecting the meter.

• Do not operate the meter with the case (or part of the case)removed.

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• Use only two “AAA” batteries, properly installed in thebattery compartment, to power the meter. Do not userechargeable batteries.

• Replace the batteries as soon as the low battery indicator“ ” appears on the LCD. Operated with weak batteries,the meter might produce false readings that could lead toelectric shock and personal injury.

• Remove the test leads from the meter before opening themeter meter’s or battery compartment.

Electrical Symbols Used On the Meterand In This Manual

Symbol Description Symbol Description

AC (Alternating FuseCurrent)

DC Double (Direct Current) Insulated

Caution, risk of Risk of danger. electric shock. ImportantHazardous information. voltage. Refer to the

manual.

Battery (Low battery) Earth groundwhen shown on display

Diode Continuity Beeper

AC or DC Complies with EU directives

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Symbol Description Symbol Description

Application and For measurementsremoval from made on building hazardous live equipment such conductors as distributionpermitted panels, feeders

and short branch circuits, and onlighting systems inlarge buildings.

SETUP INSTRUCTIONSINSTALL BATTERIESThe DMM45’s battery compartment is located at the bottomrear of the meter.

To open the compartment, use a small Phillips-headscrewdriver to remove the three silver screws securing thebattery compartment cover. Put the screws and the cover tothe side and take care not to lose the small screws.

Remove the two “AAA” batteries from the rear cavity of theblister pack. Install them in the battery compartment, takingcare to observe the polarity markings inside thecompartment.

Replace the battery compartment cover and secure it with thethree Phillips-head screws.

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OPERATING INSTRUCTIONSGENERAL INSTRUCTIONSUsing Auto Ranging. The DMM45 is an auto rangingmultimeter that cannot be operated in manual ranging mode.The meter automatically chooses the full-scale measurementrange that maximizes measurement resolution for allmeasured parameters (except temperature, for which there is only one full-scale range). The Specifications section on pages 14 & 15 lists the full-scale ranges (and theirresolutions) available for measuring DC volts, AC volts, AC amps, DC amps and resistance (in ohms).

Turning On the BacklightPressing and holding the LIGHT button (Fig. 1, Callout 2) for at least 3 seconds turns on the LCD’s bright white backlight,making measurements much easier to read in dark spaces.To extend battery life, the backlight is automatically turned off after 15 seconds.

Auto Power OffThe DMM45 is equipped with an Auto Power Off (APO) circuitthat automatically powers off the meter if no front-panelbutton is pressed within any span of 15 minutes. The purposeof the APO feature is to extend battery life.

The meter announces that APO shutdown is imminent byproducing five short beeps after 14 minutes of inactivity. To keep the meter from shutting down, immediately press theLIGHT button or change the position of the rotary functionswitch. After 15 minutes of inactivity, the APO function willshut down the meter and announce the action with a longbeep.

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MEASURING AC OR DC VOLTAGE WARNING

Do not measure any voltage higher than 500V. Doing so mayblow the meter’s internal fuse and/or damage the meter’sinternal circuitry.

(1) Set the rotary function switch to the (DC voltage) or(AC voltage) position. If you choose the position, DC

will appear on the left side of the LCD (see Fig. 2). If youchoose the position, AC will appear on the left side ofthe LCD.

(2) Plug the red test lead into the V/Ω/mA jack on the front ofthe meter and the black test lead into the COM jack.

(3) Touch the black test lead to the lower-potential point ofthe circuit under test, and the red test lead to the higher-potential point.

(4) Read the measured voltage amplitude on the LCD. If thetest leads are reversed, a minus sign will appear at the leftof the displayed value.

MEASURING AC OR DC CURRENT WARNING

Before inserting test leads into a circuit, remove power fromthe circuit.

(1) Set the rotary function switch to the position.

(2) Using the SHIFT button, select DC or AC currentmeasurement mode (indicated by the presence of DC orAC on the left side of the LCD).

(3) Plug the red test lead into the V/Ω/mA jack on the front ofthe meter and the black test lead into the COM jack.

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(4) Connect the test leads in series with the device whosecurrent flow you wish to measure.

(5) Read the measured current amplitude on the LCD. If thetest leads are reversed, a minus sign will appear at the leftof the displayed value. If the amplitude of the current youare measuring is greater than 200mA, OL (for overload)will appear on the LCD. If your readings are consistentlyless than 0.2mA, turn the rotary function switch to the

position to improve your measurement resolution.

MEASURING RESISTANCE WARNING

To avoid electrical shock or damage to the meter whenmeasuring resistance or continuity in a circuit, make sure thepower to the circuit is turned off and all capacitors aredischarged.

(1) Turn the rotary function switch to the Ω position.

(2) Plug the red test lead into the V/Ω/mA jack on the front ofthe meter and the black test lead into the COM jack.

(3) Measure the resistance by touching the tips of the leadsacross the resistor or between the desired test points ofthe circuit, as shown below.

(4) Read the measured resistance on the LCD. If themeasured resistance is greater than 20MΩ, O.L willappear on the LCD to indicate an overload.

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RED TEST LEAD BLACK TEST LEAD

MEASURING TEMPERATURE(1) Turn the rotary function switch to the °F or °C position.(2) Plug the two-prong connector of the supplied “K” type

thermocouple probe into the jacks on the front of themeter. Make sure to plug the prong labeled + into theV/Ω/mA jack and the prong labeled - into the COM jack.

(3) Read the temperature on the LCD. To quickly switch from°F to °C or vice-versa, press the SHIFT button.

CHECKING FOR CONTINUITY(1) Turn the rotary function switch to the position. An

icon of a diode will appear at the lower left of the LCD.

(2) Press the SHIFT button. The icon of a diode will change tothe continuity icon ( ). Until the test leads are pluggedinto the meter’s front-panel jacks, OL. will appear on theLCD to indicate an open circuit.

(3) Plug the red test lead into the V/Ω/mA jack on the front ofthe meter and the black test lead into the COM jack.

(4) Touch the test leads to any two points of a circuit. If theresistance between those points is <30Ω, the beeper willsound continuously. If there is no continuity (an opencircuit or a resistance greater than 30Ω between the twopoints), OL. will appear on the LCD.

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CHECKING THE INTEGRITY OF A DIODE(1) Turn the function switch to the position. An icon of

a diode will appear at the lower left of the LCD. Until thetest leads are plugged into the meter’s front-panel jacks,.OL will appear on the LCD to indicate an open circuit.

(2) Plug the red test lead into the V/Ω/mA jack on the front ofthe meter and the black test lead into the COM jack.

(3) Connect the red test lead to the anode (positive terminal)of the diode to be tested, and the black test lead to itscathode (negative terminal).

(4) Read the forward bias voltage value on the LCD. A silicondiode typically has a forward bias voltage of 0.7V. Agermanium diode typically has a forward bias voltage of0.3V. A 0V reading in both directions indicates a shorteddiode. A reading of 1 indicates an open diode. In eithercase, the diode is defective and should be replaced.

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RED TEST LEAD BLACK TEST LEAD

SPECIFICATIONSParameter orFeature/Function Specification ValueAC voltage Measurement 0 to 200mV/2V/20V/200V/500V

rangesMeasurement 0.1mV/1mV/10mV/100mV/1VresolutionsMeasurement ±(0.8% of reading + 5 digits)accuracy

DC voltage Measurement 0 to 200mV/2V/20V/200V/500Vranges

Measurement 0.1mV/1mV/10mV/100mV/1VresolutionsMeasurement ±(0.5% of reading + 5 digits)accuracy

AC current Measurement 0 to 200μA/2mA/20mA/200mAranges

Measurement 0.1μA/1μA/10μA/100μAresolutionsMeasurement ±(1.8% of reading + 3 digits)accuracy

DC current Measurement 0 to 200μA/2mA/20mA/200mAranges

Measurement 0.1μA/1μA/10μA/100μAresolutionsMeasurement ±(1.8% of reading + 2 digits)accuracy

Resistance Measurement 0 to 200Ω/2kΩ/20kΩ/200kΩ/2MΩ/20MΩranges

Measurement 0.1Ω/1Ω/10Ω/100Ω/1kΩ/10kΩresolutionsMeasurement ±(1.5% of reading + 2 digits)accuracy

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Parameter orFeature/Function Specification ValueTemperature Measurement -40° to 752°F (-40° to 400°C)

rangeMeasurement 1° (F or C)resolution

Measurement ±(8% of reading + 8 digits) below 32°F (0°C); ±(1.2% of reading + 7 digits) from 32° to 212°F (0° to100°C); ±(3% of reading + 3 digits)from 212° to 752°F (100° to 400°C)

Continuity threshold <30ΩOverload protection level 600VAC/DCInput impedance 10MΩFrequency response 50/60HzIngress protection (IP) rating IP20Safety rating CAT III 600VTest leads Double-insulated, 20 AWG,

1A max ratingDisplay No. of digits 3-1/2

Maximum count 2000Size 2.4 x 1 in. (62 x 26mm)

Digit height 0.63 in. (16mm)Auto Power Off trigger 15 minutes of front-panel inactivityBacklight duration 15 secondsOperating temperature 32° to 122°F (0° to 50°C)@<75%RHOperating altitude (max) 6562 ft. (2000m)Dimensions 8.86 x 3.31 x 1.30 in.

(225 x 84 x 33mm)Weight (including batteries) 6.3 oz. (179g)Power source (2) “AAA” batteries (IEC LR03)Battery life 200 hours (typical)

Note: Accuracy values stated for operation at 23° ±3°C @<70%RH

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accuracy

OPERATING & MAINTENANCE TIPSWhen the icon appears at the upper right of the LCD (see Fig. 2), it’s time to replace the two “AAA” batteries thatpower the meter (although measurements will remain validfor several hours after the icon first appears). To replace thebatteries, follow the instructions on p. 8.

Do not operate the DMM45 in the presence of a flammable orexplosive gas or near an arc welder or induction heater.

After subjecting the meter to a large change in ambienttemperature, wait at least 30 minutes before makingmeasurements to guarantee the accuracy of readings.

Remove the batteries when storing the meter or when you donot expect to use it for an extended period of time (monthsrather than weeks).

Do not disassemble the DMM45 or immerse it in water.REPLACING THE FUSEThe DMM45 is equipped with a 200mA/250V cylindrical fusein series with the V/Ω/mA jack.The fuse is located in the battery compartment, above thetwo “AAA” batteries (see photo below).

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To replace the fuse, open the battery compartment byremoving the three screws securing its cover. Be careful notto shatter the glass of the blown fuse when removing it, andtake care not to lose the small screws after opening thecompartment.

WARRANTY INFORMATIONGeneral Tools & Instruments’ (General’s) DMM45 AutoRanging CAT III 600V Digital Multimeter is warranted to theoriginal purchaser to be free from defects in material andworkmanship for a period of one year. Subject to certainrestrictions, General will repair or replace this instrument if,after examination, the company determines it to be defectivein material or workmanship. The warranty period begins onthe date of purchase. You are encouraged to register yourproduct online. General will extend your warranty anadditional 60 days if you register atwww.generaltools.com/ProductRegistry.

This warranty does not apply to damages that Generaldetermines to be from an attempted repair by non-authorizedpersonnel or misuse, alterations, normal wear and tear, oraccidental damage. The defective unit must be returned toGeneral Tools & Instruments or to a General-authorizedservice center, freight prepaid and insured.

Acceptance of the exclusive repair and replacement remediesdescribed herein is a condition of the contract for purchase ofthis product. In no event shall General be liable for anyincidental, special, consequential or punitive damages, or forany cost, attorneys’ fees, expenses, or losses alleged to be aconsequence of damage due to failure of, or defect in anyproduct including, but not limited to, any claims for loss ofprofits.

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Register now at www.generaltools.com/ProductRegistry toreceive a 60-day extension to your warranty.

RETURN FOR REPAIR POLICYEvery effort has been made to provide you with a reliableproduct of superior quality. However, in the event yourinstrument requires repair, please contact our CustomerService to obtain an RGA (Return Goods Authorization)number before forwarding the unit via prepaid freight to theattention of our Service Center at this address:

General Tools & Instruments80 White StreetNew York, NY 10013212-431-6100

Remember to include a copy of your proof of purchase, yourreturn address, and your phone number and/or e-mailaddress.

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GENERAL TOOLS & INSTRUMENTS80 White Street

New York, NY 10013-3567PHONE (212) 431-6100 FAX (212) 431-6499

TOLL FREE (800) 697-8665e-mail: sales@generaltools.com

www.generaltools.comDMM45 User’s Manual

Specifications subject to change without notice©2013 GENERAL TOOLS & INSTRUMENTS

NOTICE - WE ARE NOT RESPONSIBLE FOR TYPOGRAPHICAL ERRORS.MAN# DMM4510/03/13